I don't get why they're being picky about the trans tag, there's a richardgirl tag and a cuntboy tag, and in terms of art, it's the same thing in the end, so having a 'trans' tag would be redundant, and their other reasoning for being on the 'Do not post' list is too vague to judge, so from my overall perspective, this is a sucky reason to have your art removed from the site
not that this reflects my own opinions, but richardgirl, cuntboy, herm, etc. are seen as derogatory terms in the transgender community (though you might've heard that before). it's the equivalent of calling a gay person a friend, although your opinion of how offensive that is might be different, too. it's not a perspective you see a lot of on the blockland forums, in fact its one that most people here reject and make fun of, and it's certainly not a majority of people's opinions on the internet, but it's a very strongly held opinion within the online lgbt/furry community. of course, you're allowed to form your own opinions about those words, so i'm just stating that i know that a lot of lgbt or in-support-of-lgbt artists are aware of that and it generally puts them off of wanting their art on e621, since the terms used on the site have been in use since 2007 when they weren't as significant as they are now.
in my personal opinion, it makes sense that the context and meaning of words change and sometimes you have to adapt to that. i know the platform e621 is on is capable of adjusting phrases with new definitions and aliases without making the old ones useless, so i think an administrative effort could be made by e6 to change what terms default to in respect for the artists that e6 relies on. should that happen? dunno, that's for the community and the e6 team to decide.
on the flip side: i think sorimori specifically tends to have a pretty flippant attitude about things online, where if something doesn't align with their personal preferences they're more likely to just block, ignore, and make jokes about something like it isn't a big deal rather than try to understand or compromise with people. it's the kind of stubborn where there wouldn't be any good in trying to convince them otherwise, which is a shame, but i guess that's just how it is. in the end, i'm not sure i agree with them putting themselves on the DNP list either.